Mixing apparatus



May K9, 1933.

K. s. vALENj'lNE MIXING APPARATUS 3 Sheets-Sheet l Filed Oct. .'50, 19300 May 9, 1933. K. s. VALENTINE 1,908,002

MIXING APPARATUS Filed 00ct. so. 1930 Y 3 sheets-sheet 2 INVENTOR //waATTORNEYS MIXING APPARATUS Filed oct. so, 1930 3 sheets-sheet 3 INVENTORff/04d' /viA ATTORNEYS Patented May 9, 1933 narran teoaooz HINNFTH S.VALENTINE, @E HOLLIS, NEW YORK, ASSCGNF, T@ EME TURBU-MIKLERCQRPQRATION, NEW EURE, itl.- 'A GOREQFLATXtlN @F NEW YORK tramiteazz-iranienne Fpplication filed ctohcr 30, 1.930. @aerial No.. 492,19@

This invention relates to mixing apparatus. lt may be used for mixingtrue liquids, but is particularly adapted for mixing materials of aclass that have been recently denominated pseudo-plastics. Asillustrative of pseudoplastic, mention maybe made of heavy dat Whitepaint, asphalt emulsions, and clay slurries. Paper pulp also exhibitssome of the characteristics of pseudo-plastics.

To efect rapid and thorough mixing, it is necessary that currentsshall'be caused to flow in such manner that the currents interminglewith one another and eect a complete shifting and intermingling of allof the elementary volumes that make up the entire volume of material.For eihcient operation the currents must be induced smoothly and flowsmoothly, Without thelformation of areas of vacuum and without splashingor churning otherwise'a heavy braking action is imposed on the movingparts of the apparatus, thus re-f quiring the expenditure of a largeamount of power.

' general object of the invention is to provide mixing apparatus whichwill quickly and thoroughly mix 'a Vquantity of material with a minimumexpenditure of power.

` Another object of the invention is to provide mixing. apparatusparticularly suited for mixing pseudo-plastics and suspensions offibrous sollds in water or other liquids.

lA furtherobject of the invention is to'provide simple, effective andefficient mixing apparatus which will operate/smoothly, withoutvibration. i

Other objects of the inventionwill be obvious from the followingdescription taken in connection with the accompanying drawings.

In the forms of the invention disclosed, a rotary shaft carries one ormore impellers comprising a circular flow directing plate concentricwith the shaft andcarrying mvolute impeller blades. The l'iow directingplate is inclined with respect to a plane perpendicular to the shaft, sothat Vas the impeller rotates, wave motion is set up in the mass ofmaterial. This wave motion greatly accelerates the mixing action withthe result that a thorou h mixing is obtained in a very short time. heimpellers specifically disand 3 of the drawings.

closed are provided with shrouding, which 1s advantageous m mixingcertain materials.

For mixing other materials e. g. paper pulp)` the shroudingis preferablyomitted.

Fig. 1 of the drawings is a fragmentary vertical section showing oneform of the present invention.

Fig. 2 is a section taken on line 2 2 of 1l, on which is mounted amixing impeller designated as a whole by12. Impeller 12 may be made upof several separate parts, but is shown as cast in onepiece. Theimpeller comprises a hub 14, surrounded by a circular flow directingp1ate`15, from which projects a series of involute impeller blades 16.Carried by the blades is shroudingas at 17 and 18. l

As best shownin Fig. 1, liow directing plate 15 isv inclinedwi'threspect to a plane perpendicular to shaft 11. As the impellerrotates, the discharge along any given radius of the tankgraduallyshifts from a downward inclined direction to an upwardly inclineddirection and then back to a downwardly inclined directiom- Thisshifting of the direction of discharge of the impeller takes placegradually' and cyclically, thereby causing a smoothvertical wavemotionin the material being mixed. This wave 'motion greatly accentuates themixing action, without placing any substantial braking force on theimpeller; i

In the form of impeller shown in Figs. i 1, 2 and 3, all of the impellerblades start at,

a distance from the hub and extend to a considerable distance beyond theedge of ow directing plate 15. The impeller shown in Fig. 4 differs inthat only alternate blades 20 are similar to-the blades' 1 6 in Figs. 1to 3, while the intermediate blades 21 begin at the hub 22 and extendclear across and beyond plate 23. Shrouding is provided at 24 and 25.For mixing some materials, the

5 form of impeller shown in Figs. 1 to 3 is preferable, and for mixingother materials the form shown in Fig. 4 is preferable.

ln Fig. 5 a tank or container has depending therein a shaft 31,-providedwith two impellers designated as a whole by 32 and 33, respectively. Thelower portion of the shaft may be reduced as at 31; the impellersseparated by a spacing sleeve 34 and clamped by a nut 35. Each of theimpellers shown .in this figure is of the same construction as theimpeller shown in Figs. 1, 2 and 3, inclusive. The impellers arepreferably mounted on shaft 31 in corresponding rotative position asshown in the drawings, but may be mounted 180 apart. Both impellersrotate in the same direction and at the same speed. Each of theimpellers sets up a vertical wave motion in the material being mixed;and the interaction between the two sets of waves results in anexceedingly rapid and thorough mixing. Since both impellers rotate inthe same '.direction, the inter-action between the two wave motionstakes place smoothly, without agitation or churning.

As clearly shownv in Fig. 1, material is drawn into the impeller fromboth top and bottom, and. is directly outwardly by the flowdirectingplate 15,.andblades 16. The dispeller'until it has passed aconsiderable distance beyond the periphery of the How directing plate15. Thus the streams coming from the top and bottom of the tank will somix that some of the material from the bottom of the tank will bedischarged to the top of theftank, and vice versa.

This action is greatly accentuated by the tilt of flow directing plate15. Consider the right hand side of the impeller for the instant shownin Fig. 1.. Half of the intake of the impeller comes from the top of thetank and half comes from the bottom of the tank; but since the directionof discharge is inclined downwardly, the major portion oftheinstantaneous discharge is to the bottom of the tank. Conversely for theleft hand side of the impeller for the instant shown in Fig.

1. Half of the intake is from theftop of the n tank, and half from thebottom of the tank; but since the direction of discharge is inclinedupwardly, the maj or portion of the instantaneousdischarge is to the topof the tank. Thus the net result for the entire impeller is that a veryflarge portion ofY the i material drawn from the bottom of the tank isdischarged to the top of the tank, and vice versa.

The amplitude of the vertical wave motion is determined by theiangle ofinclination of s the flow directing plate 15. The optimum chargedmaterial is not released by the im.

angle of inclination varies somewhat with the particular material beingmixed, but 1 found that for. most purposes an angle between 4 and Z1/fis preferable. too great, churning action results, which laces a heavybraking action upon the impeller. I have found if the angle-be increasedbeyond 25, this churning action becomes very objectionable.

To obtain smooth action the impeller should be balanced, both`statically and dynamically. The dynamic balance should take intoconsideration, the kinetic energy of the currentsmoving against theimpeller, so that there will be no tendency for the impeller to vibrate,shift its center of rotation,

If the angle be or place a bending moment on the shaft, when theimpeller is in operation.

It is realized that the present invention may be embodied in forms otherthan those particularly disclosed, and hence the present disclosure ismerely illustrative in compliance with the patent statutes and is not tobe considered as limiting. f

What I claim is:

1. Non-churning mixing apparatus com` prising a shaft; a flow directingplate carried by said shaft, said plate being inclined approximately 6degrees with respect to a plane perpendicular to the shaft; and aplurality of vinvolute impeller blades projecting from opposite sides ofsaid plate.

2. Non-churning mixing apparatus comf prising a shaft; a flow directingplate carried by said shaft, said plate being inclined approximately 6degrees with respect'to a plane perpendicular to said shaft; and aplurality of impeller blades projecting outwardl beyond the edge of saidplate.

3. lyon-churning mixing apparatus coinprising a shaft; a flow directingplate carried by said shaft, said plate being inclined approximately 6degrees with respect to a plane perpendicular to said shaft; a pluralityof impeller blades projecting out prising a shaft; a plurality ofimpellerVY blades rotatable with said Shaft, said blades being disposedwith their center lines in a plane inclined at an angle of 4to 10degrees with respect to a plane perpendicular to the shaft; and shroudmgcarried by said blades.

6. Non-churning mixing apparatus comprising a shaft, a flow'directingplate carried by said shaft, said plate being inclined at an angle of 4to 71/2 degrees with respect to a plane perpendicular to the shaft; aplurality of involute impeller blades projecting from opposite sides ofsaid plate; and shrouding carried by said blades.

7. Mixing apparatus comprising a hub; a substantially circular plateconcentric with said hub, said plate being inclined with respect to aplane perpendicular to the axis of said hub; and a plurality of involuteimpeller blades projecting from said plate, certain of said bladesextending to said hub and other of said blades terminating short of saidhub.

8. Mixing apparatus comprising a hub; a substantially circular plateconcentric with said hub, said plate being inclined approximately 6degrees with respect to a plane perpendicular to the axis of said hub;and a plurality of involute impeller blades projecting from said plate,certain of said blades extending to said hub and other of said bladesterminating short of said hub.

9. Non-churning mixing apparatus com prising a hub; a substantiallycircular plate concentric with said hub, said plate being inclinedapproximately 6 degrees with respect to a plane perpendicular to theaxis of said hub; and a plurality of involute impeller blades projectingfrom opposite sides of said plate and substantially perpendicularthereto. f

10. Non-churning mixing apparatus comprising a shaft; a-plurality offlow directing plates mounted in spaced relation on said shaft forrotation in the same direction, each of said plates being inclined withrespect to a plane perpendicular to the axis of the shaft; and aplurality of impeller blades projecting from each of said plates.

11; Non-churning mixing apparatus comprising a shaft; a plurality offlow directing plates mounted in spaced relation on said shaft forrotation in the same direction, each of said'plates being inclined withrespect to a plane perpendicular to the axis of the shaft and the platesbeing parallel to one another; `.and a plurality of impeller bladesprojecting from each of said plates.

12. Non-churning mixing apparatus comprising a shaft; a plurality offlow directing plates mounted in spaced relation on said shaft forrotation in the same direction, each of said plates being inclined withrespect to a plane perpendicular to the axis of the shaft; and aplurality of involute impeller blades projecting from opposite sides ofeach of said plates.

13. Non-churning mixing apparatus comprising a shaft; a plurality ofliow directing plates mounted in spaced relation on said shaft forrotation in the same direction, each of said plates being inclined withrespect to a plane perpendicular to the axis of the shaft and the platesbeing parallel to one another; and a plurality of involute impellerblades projecting from opposite sides of each of said plates.

14. Non-churning mixing apparatus comprising a shaft; and a plurality ofimpellers mountedin spaced relation on said shaft for rotation in thesame direction, each of said impellers comprising a plurality of bladeshaving their center lines located in a plane which is inclined withrespect to a plane perpendicular to said shaft, and shrouding carried bysaid blades.

15. The method of mixing a body of Huid material without churning thesame which comprises drawing two main streams of the material toward oneanother from opposite directions, subdividing each of the main streamsinto a plurality of secondary streams, discharging the secondary streamsin directions outwardly of the main streams while commmgling thesecondary streams from one mam stream with respective secondary streamsfrom the other main stream, and gradually and cyclically shifting theangle between the secondary streams and the main streams.

16. The method of mixing a body of fluid i material without churning thesame which comprises establishing an annular generally horizontal mixingzone; drawing two main streams of material to the zone, one from abovethe zone and the other from beneath theY zone; mixing material from onestream with material from the other stream in proporj tions varying indifferent parts of the mixing zone; discharging obliquely upwardly theelemental streams ofthe mix containing a preponderance of material drawnfrom beneath the mixing zone; and discharging obliquely downwardly theelemental streams of the -mix containing a preponderance of materialdrawn from above the mixing zone.

17. Non-churning mixing apparatus comprising a shaft; a flow directingplate carried y said shaft, said plate being inclined at an angle of A4to 10 degrees with respect to a plane perpendicular to the shaft; and aplurality of involute impeller blades projecting from opposite sides ofsaid v late.

\ KENNETH S. VALENTINE.

